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ConfigurationPropertyAttribute Class

 

Declaratively instructs the .NET Framework to instantiate a configuration property. This class cannot be inherited.

Namespace:   System.Configuration
Assembly:  System.Configuration (in System.Configuration.dll)

System.Object
  System.Attribute
    System.Configuration.ConfigurationPropertyAttribute

[AttributeUsageAttribute(AttributeTargets.Property)]
public sealed class ConfigurationPropertyAttribute : Attribute

NameDescription
System_CAPS_pubmethodConfigurationPropertyAttribute(String)

This API supports the product infrastructure and is not intended to be used directly from your code. Initializes a new instance of ConfigurationPropertyAttribute class.

NameDescription
System_CAPS_pubpropertyDefaultValue

Gets or sets the default value for the decorated property.

System_CAPS_pubpropertyIsDefaultCollection

Gets or sets a value indicating whether this is the default property collection for the decorated configuration property.

System_CAPS_pubpropertyIsKey

Gets or sets a value indicating whether this is a key property for the decorated element property.

System_CAPS_pubpropertyIsRequired

Gets or sets a value indicating whether the decorated element property is required.

System_CAPS_pubpropertyName

Gets the name of the decorated configuration-element property.

System_CAPS_pubpropertyOptions

Gets or sets the ConfigurationPropertyOptions for the decorated configuration-element property.

System_CAPS_pubpropertyTypeId

When implemented in a derived class, gets a unique identifier for this Attribute.(Inherited from Attribute.)

NameDescription
System_CAPS_pubmethodEquals(Object)

This API supports the product infrastructure and is not intended to be used directly from your code. Returns a value that indicates whether this instance is equal to a specified object.(Inherited from Attribute.)

System_CAPS_pubmethodGetHashCode()

Returns the hash code for this instance.(Inherited from Attribute.)

System_CAPS_pubmethodGetType()

Gets the Type of the current instance.(Inherited from Object.)

System_CAPS_pubmethodIsDefaultAttribute()

When overridden in a derived class, indicates whether the value of this instance is the default value for the derived class.(Inherited from Attribute.)

System_CAPS_pubmethodMatch(Object)

When overridden in a derived class, returns a value that indicates whether this instance equals a specified object.(Inherited from Attribute.)

System_CAPS_pubmethodToString()

Returns a string that represents the current object.(Inherited from Object.)

NameDescription
System_CAPS_pubinterfaceSystem_CAPS_privmethod_Attribute.GetIDsOfNames(Guid, IntPtr, UInt32, UInt32, IntPtr)

Maps a set of names to a corresponding set of dispatch identifiers.(Inherited from Attribute.)

System_CAPS_pubinterfaceSystem_CAPS_privmethod_Attribute.GetTypeInfo(UInt32, UInt32, IntPtr)

Retrieves the type information for an object, which can be used to get the type information for an interface.(Inherited from Attribute.)

System_CAPS_pubinterfaceSystem_CAPS_privmethod_Attribute.GetTypeInfoCount(UInt32)

Retrieves the number of type information interfaces that an object provides (either 0 or 1).(Inherited from Attribute.)

System_CAPS_pubinterfaceSystem_CAPS_privmethod_Attribute.Invoke(UInt32, Guid, UInt32, Int16, IntPtr, IntPtr, IntPtr, IntPtr)

Provides access to properties and methods exposed by an object.(Inherited from Attribute.)

You use the ConfigurationPropertyAttribute to decorate a configuration property, which will instruct the .NET Framework to instantiate and to initialize the property using the value of the decorating parameter.

System_CAPS_noteNote

The simplest way to create a custom configuration element is to use the attributed (declarative) model. You declare the custom public properties and decorate them with the ConfigurationPropertyAttribute attribute. For each property marked with this attribute, the .NET Framework uses reflection to read the decorating parameters and create a related ConfigurationProperty instance. You can also use the programmatic model, in which case it is your responsibility to declare the custom public properties and return their collection.

The .NET Framework configuration system provides attribute types that you can use during the creation of custom configuration elements. There are two kinds of attribute types:

  1. The types instructing the .NET Framework how to instantiate the custom configuration-element properties. These types include:

  2. The types instructing the .NET Framework how to validate the custom configuration-element properties. These types include:

The following example shows how to define the properties of a custom ConfigurationSection object using the ConfigurationPropertyAttribute attribute.

The example contains two classes. The UrlsSection custom class uses the ConfigurationPropertyAttribute to define its own properties. The UsingConfigurationPropertyAttribute class uses the UrlsSection to read and write the custom section in the application configuration file.

using System;
using System.Configuration;


// Define a custom section.
// This class shows how to use the ConfigurationPropertyAttribute.
public class UrlsSection : ConfigurationSection
{
    [ConfigurationProperty("name", DefaultValue = "Contoso",
        IsRequired = true, IsKey = true)]
    public string Name
    {
        get
        {
            return (string)this["name"];
        }
        set
        {
            this["name"] = value;
        }
    }

    [ConfigurationProperty("url", DefaultValue = "http://www.contoso.com",
        IsRequired = true)]
    [RegexStringValidator(@"\w+:\/\/[\w.]+\S*")]
    public string Url
    {
        get
        {
            return (string)this["url"];
        }
        set
        {
            this["url"] = value;
        }
    }

    [ConfigurationProperty("port", DefaultValue = (int)0, IsRequired = false)]
    [IntegerValidator(MinValue = 0, MaxValue = 8080, ExcludeRange = false)]
    public int Port
    {
        get
        {
            return (int)this["port"];
        }
        set
        {
            this["port"] = value;
        }
    }
}
using System;
using System.Configuration;

public class UsingConfigurationPropertyAttribute
{

    // Create a custom section and save it in the 
    // application configuration file.
    static void CreateCustomSection()
    {
        try
        {

            // Create a custom configuration section.
            UrlsSection customSection = new UrlsSection();

            // Get the current configuration file.
            System.Configuration.Configuration config =
                    ConfigurationManager.OpenExeConfiguration(
                    ConfigurationUserLevel.None);

            // Add the custom section to the application
            // configuration file.
            if (config.Sections["CustomSection"] == null)
            {
                config.Sections.Add("CustomSection", customSection);
            }


            // Save the application configuration file.
            customSection.SectionInformation.ForceSave = true;
            config.Save(ConfigurationSaveMode.Modified);

            Console.WriteLine("Created custom section in the application configuration file: {0}",
                config.FilePath);
            Console.WriteLine();

        }
        catch (ConfigurationErrorsException err)
        {
            Console.WriteLine("CreateCustomSection: {0}", err.ToString());
        }

    }

    static void ReadCustomSection()
    {
        try
        {
            // Get the application configuration file.
            System.Configuration.Configuration config =
                    ConfigurationManager.OpenExeConfiguration(
                    ConfigurationUserLevel.None) as Configuration;

            // Read and display the custom section.
            UrlsSection customSection =
                config.GetSection("CustomSection") as UrlsSection;
            Console.WriteLine("Reading custom section from the configuration file.");
            Console.WriteLine("Section name: {0}", customSection.Name);
            Console.WriteLine("Url: {0}", customSection.Url);
            Console.WriteLine("Port: {0}", customSection.Port);
            Console.WriteLine();
        }
        catch (ConfigurationErrorsException err)
        {
            Console.WriteLine("ReadCustomSection(string): {0}", err.ToString());
        }

    }

    static void Main(string[] args)
    {

        // Get the name of the application.
        string appName =
            Environment.GetCommandLineArgs()[0];

        // Create a custom section and save it in the 
        // application configuration file.
        CreateCustomSection();

        // Read the custom section saved in the
        // application configuration file.
        ReadCustomSection();

        Console.WriteLine("Press enter to exit.");

        Console.ReadLine();
    }
}

The following is an excerpt of the configuration file containing the custom section as defined in the previous sample.

<?xml version="1.0" encoding="utf-8"?>
<configuration>
    <configSections>
        <section name="CustomSection" type="UrlsSection, UsingConfigurationPropertyAttribute, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null" />
    </configSections>
    <CustomSection name="Contoso" url="http://www.contoso.com" />
</configuration>

.NET Framework
Available since 2.0

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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